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Anatomy > Cell 1 > Flashcards

Cell 1 Flashcards

1
Q

What are the types of proteins in the plasma membrane?

A

Integral proteins- embedded in or pass through lipid bilayer

Peripheral proteins- associate with membrane lipids or integral membrane proteins

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2
Q

What are the 3 major classes of lipids? What percentage does each make up?

A
  1. Phospholipids (~75%)
  2. Cholesterol (~20%)
    • Intercalates between phospholipids
    • reduces membrane fluidity
  3. Glycolipids(~5%)
    - Sugar-containing lipid molecules
    - Found exclusively in outer monolayer
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3
Q

Describe plasma membrane lipids

A

~50% membrane mass

  • Amphipathic
    • Hydrophilic “water-loving” polar head
    • Hydrophobic “water-fearing” nonpolar tail
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4
Q

Contrast integral and membrane proteins

A
  1. Integral membrane proteins
    - transmembrane
    • single pass and multi pass
      • Anchored
    • alpha helix
    • lipid chain
    • oligosaccharide linker
  2. Peripheral membrane proteins
    • Noncovalent association with integral membrane proteins
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5
Q

What are the general categories of integral membrane proteins?

A
  1. Pumps/carriers/transporters
  2. Channel
  3. Receptors
  4. Linkers
  5. Enzymes
  6. Structural proteins
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6
Q

Describe pumps/carriers/transporters as a category of integral membrane proteins

A

Transport specific ions across the membrane

  • sodium
  • Potassium

Transport metabolic precursors

  • Amino acids
  • Sugars
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7
Q

Describe channels as integral membrane proteins

A

Transport of ions, small molecules and water
-passive diffusion

Aqua porins
-water

Gap junctions
-passage of ions, small molecules between adjacent cells

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8
Q

What is the structure of the membrane ?

A

Fluid mosaic model

  • fluid membrane
  • lipids and proteins have ability to move within the plane of the membrane
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9
Q

What are the properties of the membrane?

A

Fluidity

  • membrane lipids and proteins are mobile
  • Cholesterol serves to stabilize the membrane
    • Reduce membrane fluidity

Selective permeability

  • Permeable
    • Hydrophobic, non-polar, uncharged molecules
    • oxygen, carbon dioxide
  • Less permeable
    • small, polar, uncharged molecules
    • water
  • highly permeable
    • charged (ions), polar molecules

Transmembrane proteins

  • channels and transporters
    • increase the permeability of the membrane to molecules that cannot cross the lipid bilayer
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10
Q

What factors influenced diffusion?

A
  • concentration gradient
  • size or mass of the diffusing substance
  • temperature
  • surface area
  • diffusion distance
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11
Q

Plasma membrane is a barrier to…

A

Diffusion

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12
Q

What is osmosis?

A

Diffusion of water across a semi-permeable membrane(doesn’t allow dissolved solutes to pass )

-movement from low solute concentration to high solute concentration

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13
Q

What is osmotic pressure?

A
  • pressure that must be applied to prevent the flow of water across the semi-permeable membrane
  • proportional to the concentration of the solute particles that cannot cross the membrane
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14
Q

What is osmoregulation?

A

Cellular mechanism to reach a balance in osmotic pressure/homeostasis

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15
Q

What is tonicity?

A

Measure of the osmotic pressure of 2 solutions separated by a semi-permeable membrane

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16
Q

What is an isotonic solution?

A
  • equal concentration of solutes outside and inside of the cell
  • homeostasis
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17
Q

What is an hypotonic solution?

A
  • lower concentration of solutes outside than inside the cell
  • Water enters the cell- cell swells and bursts (cytolysis)
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18
Q

What is a hypertonic solution?

A
  • higher concentration of solutes outside the cell than the inside
  • water exits the cell- cell shrinks(crenation)
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19
Q

What are the passive processes of membrane transport?

A
  • simple diffusion
  • diffusion through channel proteins
  • facilitated diffusion
    • carrier/pump/transporter
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20
Q

What are the active processes of me,Brahe transport?

A
  • primary active
  • secondary active
  • vesicular
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21
Q

What are the types of membrane transport?

A

Passive and active processes

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22
Q

Describe diffusion through the lipid bilayer

A
  • non-polar, hydrophobic molecules
  • gases
  • oxygen, carbon dioxide, nitrogen
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23
Q

Describe facilitated diffusion through channel protein

A
  • polar, hydrophilic molecules

- inorganic ions

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24
Q

Give an example of facilitated diffusion via carrier protein

A

Glucose

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25
Q

What is primary active transport?

A

-energy requiring process that moves solutes against an electrochemical gradient

  • sodium potassium pump
    • important for regulating cell volume
26
Q

Explain the functioning of the sodium-potassium pump

A
  1. 3 sodium ions from the cytosol bind to the inside surface of the sodium-potassium pump
  2. Na+ binding triggers ATP to bind to the pump and be split into ADP and P. The energy from ATP splitting causes the protein to change shape, which moves the sodium ions outside
  3. 2 potassium ions land to the outside surface of the pump and cause the P to be released
  4. The release of the P causes the pump to return to its original shape, which moves the K+ into the cell
27
Q

What is secondary active transport?

A
  • energy stored in one concentration gradient is used to drive other substances across the membrane against their own concentration gradient
    • e.g. energy (ATP) used to build their Na+ or H+ gradient used to transport glucose or amino acids across
  • use energy indirectly
  • two types of transport: anti-porters and symporters
28
Q

What are the types of vesicular transport?

A

Exocytosis and endocytosis

29
Q

What is exocytosis

A

Substance exits the cell by the fusion of a vehicle with the plasma membrane

30
Q

What is endocytosis?

A

Substance enters the cell by a vesicle formed from the plasma membrane

3 types:

  1. Receptor-mediated
  2. Pinocytosis
  3. Phagocytosis
31
Q

What are the features of exocytosis?

A
  • releases material from cells
  • occurs in all cells

Especially important for:
-secretory cells
Ex. Enzymes, hormones, mucus

  • nerve cells
    • neurotransmitters
32
Q

Explain the process of receptor-mediated endocytosis

A
  1. Binding
    - ligand binds to specific receptor
    - Clathrin recruitment
  2. Vesicle formation
    - clathrin dependent (makes a clathrin coated vesicle)
  3. Uncoating (clathrin recycled)
  4. Fusion with endosome
    - sorting of ligand and receptors
  5. Degradation
    - fusion with lysosome
33
Q

What is pinocytosis ?

A

Pino= to drink

-bulk-phase endocytosis

  • vesicle formation
    • nonspecific
    • invagination of membrane
    • Clathrin dependent
  • fusion with lysosome
  • digestion
34
Q

What is phagocytosis?

A

Phago= to eat

  • large organic and inorganic particles
    • bacteria, viruses, dead cells, debris
35
Q

Explain the process of phagocytosis

A
  1. Binding
    - ex. Antibody coated bacteria
  2. Pseudopod formation
    - actin dependent
  3. Phagosome formation
  4. Fusion with lysosome
  5. Digestion
    • lysosomal enzymes
36
Q

What is cytosol?

A
  • intracellular fluid: fluid portion that surrounds the organelles
  • 55% of cell volume
37
Q

What are the functions of cytosol?

A

Site of many chemical reactions

Mainly water with dissolved and suspended substances
-ions, glucose, fats, lipids, proteins, ATP and waste products

38
Q

What are the microfilaments made of?

A

Made of the protein actin

G-actin
-free actin molecules in the cytoplasm

F-actin

  • polymerized actin in a filament
  • ATP dependent

Polarized structures

  • fast growing (+) positive end
  • slow growing (-) negative end
39
Q

Microfilaments May exist as…

A

Single filaments, in bundles, or in networks

40
Q

What are the cell functions of microfilaments?

A
  • anchorage
  • structural core of microvilli
  • cell motility
  • extension of cell processes
41
Q

Describe the structure of intermediate filaments

A

Rope-like filaments

-structure= formed from non-polar and highly variable subunits

42
Q

What are the functions of intermediate filaments?

A

Structural

  • stabilize cell structure
    • mechanical strength
    • maintain the position
  • Resist shearing forces
    • extend across cytoplasm
    • connecting with desmosomes and hemidesmosomes

Essential for integrity of cell-cell and cell-ECM junctions

43
Q

Describe the structure of microtubules

A

Structure:

  • Non-branching, rigid, hollow tubes
    - a and B tubulin protein subunits
  • Polar
    • Minus (-) end
    • Plus(+) end
44
Q

What are the functions of microtubules?

A

Intracellular transport
-movement of vesicles and organelles

Cell motility

  • Movement of cilia and flagella
  • Cell elongation and movement

Mitotic spindle
-Attachment of chromosomes & their movement during cell division

Rigid intracellular skeleton
-maintenance of cell shape and polarity

Assemble and disassemble as the needs of the cell change

45
Q

Describe the structure of centrioles

A
  • 9 triplets of microtubules arranged around a central axis

- Each triplet consists of 1 complete and 2 incomplete microtubules fused

46
Q

What are the functions of centrioles?

A

-Organizes the Centrosome

  • basal body formation
    • provide basal bodies necessary for assembly of cilia and flagella
  • Mitotic spindle formation
    • formation of centrosome and alignment of the mitotic spindle during cell division
47
Q

What is the structure of the centrosome ?

A

Contains a pair of centrioles
-arranged such that one is perpendicular to the other

Amorphous protein matrix
- >200 proteins

Gamma-tubulin ring complexes
-Nucleation sites for microtubules

48
Q

What are the functions of centrosome?

A

Microtubules organizing center (MTOC)

Initiate microtubule formation

  • microtubules are nucleated at the centrosome at their negative (-) ends
  • Positive (+) ends point out and grow toward the cell periphery
49
Q

What are the cilia and flagella?

A

These are microtubule structures

  • motile
    • beat in synchronous pattern

-9+2 microtubule arrangement

  • pair of dynein arms
    • motor protein
    • binds adjacent microtubule

Anchored to cell via the basal body
-thin, dark-staining band at base of cilia

50
Q

What is the function of cilia and flagella?

A

Move fluid and particles along epithelial surfaces

51
Q

What is the rER?

A

Membrane bound ribosomes attached to cytoplasmic surface of the ER

  • Abundant in cells specialized in protein synthesis
    • Ex. Secretory cells producing proteins for extracellular export
52
Q

What is the sER?

A

-region of the ER that lacks bound ribosomes

  • abundant in cells specialized in lipid metabolism
    • well developed in cells that synthesize and secrete steroids
53
Q

What are the functions of sER?

A

Plays a major role in detoxification
-ex. Heoatocytes

Also functions to sequester calcium
-ex. Muscle cells and sarcoplasmic reticulum

54
Q

What is the Golgi apparatus?

A
  • complex of flattened, membrane-enclosed cisternae
  • usually located next to the nucleus and centrosome
  • each Golgi stack had 2 faces

Cis face= entry
-receives vesicles from rER

Trans face= exit

55
Q

What are the functions of the Golgi apparatus?

A
  • post transnational modifications
    • glycisylation
    • phosphorylation
    • sulfation

Sorting

Packaging

56
Q

What are the 3 destinations of the Golgi apparatus?

A

Lysosomal vesicles

Secretory vesicles

Membrane vesicles

57
Q

What are lysosomes

A

Digestive organelles

Membrane-enclosed compartments filled with ~40 types of hydrolytic enzymes

58
Q

Whaat is the function of lysosomes?

A

Controlled Intracellular digestion of macromolecules

59
Q

Describe the structure of the mitochondria

A

2 membranes- outer and inner membrane

2 compartments - inter membrane space and matrix

60
Q

What are the functions of the mitochondria?

A

Generate ATP
-citric acid cycle
-oxidative phosphorylation
— B-oxidation of fatty acids

Abundant in cells that generate and expend large amounts of energy
-ex. Striated muscle cells

Evolved from aerobic bacteria that were engulfed by primitive eukaryotic cells
- Have own DNA

61
Q

What are peroxisomes?

A

Microbodies

-small organelles (0.5 um diameter)

62
Q

What are the functions of peroxisomes ?

A

Specialized to compartmentalize and degrade toxic reactive oxygen molecules

  • contain catalase and other peroxidases
    • converts hydrogen peroxide to oxygen and water
  • particularly important in hepatocytes
    • detoxification of ingested alcohol

Anatomy (29 decks)

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